IBSP, also known as bone sialoprotein 2, is a monomeric noncollagenous member of the SIBLING family of extracellular matrix (ECM) proteins. It is synthesized by platelets, osteoblasts, osteocytes, odontoblasts, osteoclasts, and bone marrow stromal cells. It is a key mediator of the hypertrophic chondrocytes-induced angiogenesis. It was associated with the severity of histological cartilage lesions and with vascular density at the osteochondral junction. Recombinant human IBSP, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.